The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
H. L. Liao - One of the best experts on this subject based on the ideXlab platform.
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A generalized Critical Velocity window based on material property for cold spraying by eulerian method
Journal of Thermal Spray Technology, 2014Co-Authors: Wen-ya Li, F. F. Wang, Shuo Yin, Min Yu, H. L. LiaoAbstract:In this paper, the previously developed Eulerian model (Yu et al., J Therm Spray Technol 21(3):745- 752, 2012), which could well predict the Critical Velocity and erosion Velocity, was extended to other commonly used materials such as aluminum, iron, nickel, stainless steel 316, and Inconel718 for studying the influence of material property and establishing a generalized window of Critical Velocity. Results show that the deformation behavior of the used materials could be classified as coordinated deformation (copper, iron, nickel) and uncoordinated deformation patterns (aluminum, stainless steel, and Inconel718). However, it was found that the steady maximum equivalent plastic strain values at the Critical Velocity for each material concentrate in the extent of 2.6-3.0 regardless of deformation pattern. Dimensionless analysis shows that, the calculated Critical Velocity increases with the increase of material characteristic Velocity, and this relationship can be primarily used to predict the Critical Velocity.
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Prediction of Critical Velocity During Cold Spraying Based on a Coupled Thermomechanical Eulerian Model
Journal of Thermal Spray Technology, 2013Co-Authors: F. F. Wang, Min Yu, Wen-ya Li, H. L. LiaoAbstract:In cold spraying (CS), Critical Velocity of particles is one of the most important parameters. The impacting particle and substrate inevitably undergo a strong thermomechanical coupling process at the contacting interface and serious plastic deformation in a very short time. In this paper, a coupled thermomechanical Eulerian (CTM-Eulerian) model was, for the first time, developed for CS particles to investigate plastic deformation and heat conduction within the bulk, and to predict the Critical Velocity. Results show that heat conduction has a significant effect on the temperature distribution within the particle which will influence the atom diffusion at the impacting interface, while a little influence on plastic deformation. Moreover, based on the deformed particle shapes and plastic strain analysis, a calculated Critical Velocity of about 300 m/s for copper is obtained. Finally, this CTM-Eulerian model is extended to other commonly sprayed materials and the predicted Critical velocities of Fe, Ni, SS304, Al, In718, and TC4 are about 350, 380, 395, 410, 490, and 500 m/s, respectively. © 2013 ASM International.
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Influence of spray materials and their surface oxidation on the Critical Velocity in cold spraying
Proceedings of the International Thermal Spray Conference, 2009Co-Authors: Chang-jiu Li, Guan-jun Yang, Hong Tao Wang, Wen-ya Li, Qi Zhang, H. L. LiaoAbstract:The Critical Velocity is an important parameter in cold spraying, which determines the deposition efficiency under a given spray condition. The Critical Velocity depends not only on materials types, but also on particle temperature and oxidation conditions. In the present paper, three types of materials including copper, 316L stainless steel, Monel alloy were used to deposit coatings by cold spraying. The Critical velocities of spray materials were determined using a novel measurement method. The oxygen content in the three powders was changed by isothermal oxidation at ambient atmosphere. The effect of oxygen content on the Critical Velocity was examined. It was found that the Critical Velocity in cold spray was significantly influenced by particle oxidation condition besides materials properties. The Critical Velocity of Cu particles changed from about 300 m/s to over 610 m/s with the change of oxygen content in powder. It is evident that the materials properties influence the Critical Velocity more remarkable at low oxygen content than at high oxygen content. The results suggest that with a severely oxidized powder the Critical Velocity tends to be dominated by oxide on the powder surface rather than materials properties. © 2009 ASM International.
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Examination of the Critical Velocity for Deposition of Particles in Cold Spraying
Journal of Thermal Spray Technology, 2006Co-Authors: Chang-jiu Li, Wen-ya Li, H. L. LiaoAbstract:The Critical Velocity of copper (Cu) particles for deposition in cold spraying was estimated both experimentally and theoretically. An experimental method is proposed to measure the Critical Velocity based on the theoretical relationship between deposition efficiency and Critical Velocity at different spray angles. A numerical simulation of particle impact deformation is used to estimate the Critical Velocity. The theoretical estimation is based on the Critical Velocity corresponding to the particle Velocity at which impact begins to cause adiabatic shear instability. The experimental deposition was conducted using Cu particles of different particle sizes, velocities, oxygen contents, and temperatures. The dependency of the Critical Velocity on particle temperature was examined. Results show that the Critical Velocity can be reasonably measured by the proposed test method, which detects the change of Critical Velocity with particle temperature and oxygen content. The Cu particles of oxygen content 0.01 wt.% yielded a Critical Velocity of about 327 m/s. Experiments show that the oxygen content of powder significantly influences the Critical Velocity. Variations in oxygen content can explain the large discrepancies in Critical Velocity that have been reported by different investigators. Critical Velocity is also found to be influenced by particle temperature as well as types of materials. High particle temperature causes a decrease in Critical Velocity. This effect is attributed to the thermal softening at elevated temperatures. © ASM International.
Hanlin Liao - One of the best experts on this subject based on the ideXlab platform.
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prediction of Critical Velocity during cold spraying based on a coupled thermomechanical eulerian model
Journal of Thermal Spray Technology, 2014Co-Authors: F. F. Wang, Min Yu, Wen-ya Li, Hanlin LiaoAbstract:In cold spraying (CS), Critical Velocity of particles is one of the most important parameters. The impacting particle and substrate inevitably undergo a strong thermomechanical coupling process at the contacting interface and serious plastic deformation in a very short time. In this paper, a coupled thermomechanical Eulerian (CTM-Eulerian) model was, for the first time, developed for CS particles to investigate plastic deformation and heat conduction within the bulk, and to predict the Critical Velocity. Results show that heat conduction has a significant effect on the temperature distribution within the particle which will influence the atom diffusion at the impacting interface, while a little influence on plastic deformation. Moreover, based on the deformed particle shapes and plastic strain analysis, a calculated Critical Velocity of about 300 m/s for copper is obtained. Finally, this CTM-Eulerian model is extended to other commonly sprayed materials and the predicted Critical velocities of Fe, Ni, SS304, Al, In718, and TC4 are about 350, 380, 395, 410, 490, and 500 m/s, respectively.
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influence of spray materials and their surface oxidation on the Critical Velocity in cold spraying
Journal of Thermal Spray Technology, 2010Co-Authors: Chang-jiu Li, Guan-jun Yang, Haiyang Wang, Qiang Zhang, Wei Li, Hanlin LiaoAbstract:The Critical Velocity is an important parameter in cold spraying, which determines the deposition efficiency under a given spray condition. The Critical Velocity depends not only on materials types, but also on particle temperature and oxidation conditions. In the present paper, three types of materials including copper, 316L stainless steel, Monel alloy were used to deposit coatings by cold spraying. The Critical velocities of spray materials were determined using a novel measurement method. The oxygen content in the three powders was changed by isothermal oxidation at ambient atmosphere. The effect of oxygen content on the Critical Velocity was examined. It was found that the Critical Velocity in cold spray was significantly influenced by particle oxidation condition besides materials properties. The Critical Velocity of Cu particles changed from about 300 m/s to over 610 m/s with the change of oxygen content in powder. It is evident that the materials properties influence the Critical Velocity more remarkable at low oxygen content than at high oxygen content. The results suggest that with a severely oxidized powder the Critical Velocity tends to be dominated by oxide on the powder surface rather than materials properties.
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examination of the Critical Velocity for deposition of particles in cold spraying
Journal of Thermal Spray Technology, 2006Co-Authors: Chang-jiu Li, Wen-ya Li, Hanlin LiaoAbstract:The Critical Velocity of copper (Cu) particles for deposition in cold spraying was estimated both experimentally and theoretically. An experimental method is proposed to measure the Critical Velocity based on the theoretical relationship between deposition efficiency and Critical Velocity at different spray angles. A numerical simulation of particle impact deformation is used to estmate the Critical Velocity. The theoretical estimation is based on the Critical Velocity corresponding to the particle Velocity at which impact begins to cause adiabatic shear instability. The experimental deposition was conducted using Cu particles of different particle sizes, velocities, oxygen contents, and temperatures. The dependency of the Critical Velocity on particle temperature was examined. Results show that the Critical Velocity can be reasonably measured by the proposed test method, which detects the change of Critical Velocity with particle temperature and oxygen content. The Cu particles of oxygen content 0.01 wt.% yielded a Critical Velocity of about 327 m/s. Experiments show that the oxygen content of powder significantly influences the Critical Velocity. Variations in oxygen content can explain the large discrepancies in Critical Velocity that have been reported by different investigators. Critical Velocity is also found to be influenced by particle temperature as well as types of materials. High particle temperature causes a decrease in Critical Velocity. This effect is attributed to the thermal softening at elevated temperatures.
Wen-ya Li - One of the best experts on this subject based on the ideXlab platform.
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A generalized Critical Velocity window based on material property for cold spraying by eulerian method
Journal of Thermal Spray Technology, 2014Co-Authors: Wen-ya Li, F. F. Wang, Shuo Yin, Min Yu, H. L. LiaoAbstract:In this paper, the previously developed Eulerian model (Yu et al., J Therm Spray Technol 21(3):745- 752, 2012), which could well predict the Critical Velocity and erosion Velocity, was extended to other commonly used materials such as aluminum, iron, nickel, stainless steel 316, and Inconel718 for studying the influence of material property and establishing a generalized window of Critical Velocity. Results show that the deformation behavior of the used materials could be classified as coordinated deformation (copper, iron, nickel) and uncoordinated deformation patterns (aluminum, stainless steel, and Inconel718). However, it was found that the steady maximum equivalent plastic strain values at the Critical Velocity for each material concentrate in the extent of 2.6-3.0 regardless of deformation pattern. Dimensionless analysis shows that, the calculated Critical Velocity increases with the increase of material characteristic Velocity, and this relationship can be primarily used to predict the Critical Velocity.
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prediction of Critical Velocity during cold spraying based on a coupled thermomechanical eulerian model
Journal of Thermal Spray Technology, 2014Co-Authors: F. F. Wang, Min Yu, Wen-ya Li, Hanlin LiaoAbstract:In cold spraying (CS), Critical Velocity of particles is one of the most important parameters. The impacting particle and substrate inevitably undergo a strong thermomechanical coupling process at the contacting interface and serious plastic deformation in a very short time. In this paper, a coupled thermomechanical Eulerian (CTM-Eulerian) model was, for the first time, developed for CS particles to investigate plastic deformation and heat conduction within the bulk, and to predict the Critical Velocity. Results show that heat conduction has a significant effect on the temperature distribution within the particle which will influence the atom diffusion at the impacting interface, while a little influence on plastic deformation. Moreover, based on the deformed particle shapes and plastic strain analysis, a calculated Critical Velocity of about 300 m/s for copper is obtained. Finally, this CTM-Eulerian model is extended to other commonly sprayed materials and the predicted Critical velocities of Fe, Ni, SS304, Al, In718, and TC4 are about 350, 380, 395, 410, 490, and 500 m/s, respectively.
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Prediction of Critical Velocity During Cold Spraying Based on a Coupled Thermomechanical Eulerian Model
Journal of Thermal Spray Technology, 2013Co-Authors: F. F. Wang, Min Yu, Wen-ya Li, H. L. LiaoAbstract:In cold spraying (CS), Critical Velocity of particles is one of the most important parameters. The impacting particle and substrate inevitably undergo a strong thermomechanical coupling process at the contacting interface and serious plastic deformation in a very short time. In this paper, a coupled thermomechanical Eulerian (CTM-Eulerian) model was, for the first time, developed for CS particles to investigate plastic deformation and heat conduction within the bulk, and to predict the Critical Velocity. Results show that heat conduction has a significant effect on the temperature distribution within the particle which will influence the atom diffusion at the impacting interface, while a little influence on plastic deformation. Moreover, based on the deformed particle shapes and plastic strain analysis, a calculated Critical Velocity of about 300 m/s for copper is obtained. Finally, this CTM-Eulerian model is extended to other commonly sprayed materials and the predicted Critical velocities of Fe, Ni, SS304, Al, In718, and TC4 are about 350, 380, 395, 410, 490, and 500 m/s, respectively. © 2013 ASM International.
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Influence of spray materials and their surface oxidation on the Critical Velocity in cold spraying
Proceedings of the International Thermal Spray Conference, 2009Co-Authors: Chang-jiu Li, Guan-jun Yang, Hong Tao Wang, Wen-ya Li, Qi Zhang, H. L. LiaoAbstract:The Critical Velocity is an important parameter in cold spraying, which determines the deposition efficiency under a given spray condition. The Critical Velocity depends not only on materials types, but also on particle temperature and oxidation conditions. In the present paper, three types of materials including copper, 316L stainless steel, Monel alloy were used to deposit coatings by cold spraying. The Critical velocities of spray materials were determined using a novel measurement method. The oxygen content in the three powders was changed by isothermal oxidation at ambient atmosphere. The effect of oxygen content on the Critical Velocity was examined. It was found that the Critical Velocity in cold spray was significantly influenced by particle oxidation condition besides materials properties. The Critical Velocity of Cu particles changed from about 300 m/s to over 610 m/s with the change of oxygen content in powder. It is evident that the materials properties influence the Critical Velocity more remarkable at low oxygen content than at high oxygen content. The results suggest that with a severely oxidized powder the Critical Velocity tends to be dominated by oxide on the powder surface rather than materials properties. © 2009 ASM International.
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examination of the Critical Velocity for deposition of particles in cold spraying
Journal of Thermal Spray Technology, 2006Co-Authors: Chang-jiu Li, Wen-ya Li, Hanlin LiaoAbstract:The Critical Velocity of copper (Cu) particles for deposition in cold spraying was estimated both experimentally and theoretically. An experimental method is proposed to measure the Critical Velocity based on the theoretical relationship between deposition efficiency and Critical Velocity at different spray angles. A numerical simulation of particle impact deformation is used to estmate the Critical Velocity. The theoretical estimation is based on the Critical Velocity corresponding to the particle Velocity at which impact begins to cause adiabatic shear instability. The experimental deposition was conducted using Cu particles of different particle sizes, velocities, oxygen contents, and temperatures. The dependency of the Critical Velocity on particle temperature was examined. Results show that the Critical Velocity can be reasonably measured by the proposed test method, which detects the change of Critical Velocity with particle temperature and oxygen content. The Cu particles of oxygen content 0.01 wt.% yielded a Critical Velocity of about 327 m/s. Experiments show that the oxygen content of powder significantly influences the Critical Velocity. Variations in oxygen content can explain the large discrepancies in Critical Velocity that have been reported by different investigators. Critical Velocity is also found to be influenced by particle temperature as well as types of materials. High particle temperature causes a decrease in Critical Velocity. This effect is attributed to the thermal softening at elevated temperatures.
Haukur Ingason - One of the best experts on this subject based on the ideXlab platform.
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effect of cross section on Critical Velocity in longitudinally ventilated tunnel fires
Fire Safety Journal, 2017Co-Authors: Ying Zhen Li, Haukur IngasonAbstract:Numerical and theoretical work was conducted to investigate the effect of tunnel cross section on Critical Velocity for smoke control in longitudinally ventilated tunnel fires. The results show that for small fires, the Critical Velocity decreases with both the increasing tunnel height and tunnel width. For large fires, the Critical Velocity significantly increases with the increasing tunnel height but is independent of tunnel width. Different calculation models are compared with a focus on effect of tunnel cross section. A new correlation is proposed to account for the effect of tunnel width based on the previous model.
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theoretical and experimental study of Critical Velocity for smoke control in a tunnel cross passage
Fire Technology, 2013Co-Authors: Ying Zhen Li, Haukur IngasonAbstract:Theoretical analyses and model-scale experiments have been conducted to investigate the Critical Velocity in a tunnel cross-passage which is defined as the minimum ventilation Velocity through the fireproof door to prevent smoke from flowing into a cross-passage. The effect of the fireproof door geometry, heat release rate, ventilation Velocity and fire source location were taken into account. The Critical Velocity in a tunnel cross-passage varies approximately as 3/2 power of the fireproof door height, as one-third power of the heat release rate and as exponential law of the ventilation Velocity, almost independent of the fireproof door width. The Critical Froude Number mainly ranges from 5 to 10 and consequently as it is not a constant value it is not very suitable to predict the Critical Velocity in a tunnel cross-passage. A dimensionless correlation that can correlate well with the experimental data was proposed.
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study of Critical Velocity and backlayering length in longitudinally ventilated tunnel fires
Fire Safety Journal, 2010Co-Authors: Ying Zhen Li, Haukur IngasonAbstract:Experimental tests and theoretical analyses were conducted to investigate the Critical Velocity together with the backlayering length in tunnel fires. The experiments were performed in two longitudinally ventilated model tunnels. The proposed correlations for Critical Velocity are found to comply well with experimental data in both tunnels. The Critical Froude number and the Critical Richardson number were analyzed using the experimental data. The backlayering length was related to the ratio of longitudinal ventilation Velocity to Critical Velocity. Experimental data show that the relation between the ratio of ventilation Velocity to Critical Velocity and the dimensionless backlayering length follows an exponential relation. A correlation based on experimental data to predict the backlayering length is proposed. Further, comparison of experimental data of Critical Velocity and backlayering length with results from large-scale tests shows that there is a good agreement in both scales. The effect of accident vehicle obstruction on Critical Velocity and backlayering length was also analyzed. Experimental data show that the decrease in rate of Critical Velocity due to obstruction is slightly greater than the ratio of cross-sectional area of the model vehicle to tunnel cross-sectional area, and the backlayering length with an accident vehicle set inside the tunnel gets smaller.
Youlgwun Ji - One of the best experts on this subject based on the ideXlab platform.
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oxidation dependency of Critical Velocity for aluminum feedstock deposition in kinetic spraying process
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2008Co-Authors: Kicheol Kang, Sanghoon Yoon, Youlgwun JiAbstract:In kinetic spraying process, Critical Velocity is an important criterion which determines the deposition of feedstock onto the substrate. It has been proven experimentally and numerically that the Critical Velocity is determined by physical and mechanical properties and the state of materials such as initial temperature and size. In this study, the oxidation effect on Critical Velocity was investigated using experimental methods. As oxygen content of feedstock increased, Critical Velocity significantly decreased. In order to find out reasons for difference in Critical Velocity with oxygen content, individual impact behavior was analyzed and interface microstructure was observed. Due to high brittleness and hardness of oxide, oxide layer on particle influences the particle deformation behavior during impact. And oxide accumulated at interface obstructs the adhesion between activated particle and substrate surface during impact.